Contour Enthusiasts Group Archives Forums Modifications Forced Induction S/C PLUS 3.0L

They're back in the machine shop right now. The valves are being lapped in and installed after I did all the porting/widening and smoothing. He is also checking for leaks with pressure testing. I do not think he will sonic check them, but I have done almost the same thing on my BMW and he checked that out (its still running fine 2yrs now) FWIW. The machinist is very respected here in Tucson, and he says I did a good job, one of the better ones he's seen for being conservative about not cutting too close to the water jacket. I used a depth micrometer to check the depth in some of the water passages surrounding the combustion chambers. I did it in such a way as to give me a comparison between the wall thicknesses of the two heads, and there was no difference between those ports that I checked that were the same on both heads. The only differences i could see with the heads aside from the water pump drive and extra oil return, was the size of the combustion chamber and the diameter of the intake runners and valves. The 3L casting is apparently just a modified, widened 2.5L casting. i.e. the extra metal is there and can safely be removed if you are careful.

I wont swear on this to everyone as I am not going to be responsible for someone chewing up their heads. However, if you are careful not to take off more metal than the 3L heads are missing, then you should be fine. Be conservative.

warmonger

MM&FF just did a how-to on how to port your own heads. Pretty good article.

Why is everyone using the SVT heads vs. 3.0 heads? Only benefit I can see is cam timing and maybe easier installation, but you have to worry about CR. Which could actually be used to your benefit. Adv. of 3.0 heads are lower CR for forced induction, larger valves for better airflow. SVT cams will fit in 3.0 heads, correct? I'm picking up a 3.0 block this winter to build and I'm trying to decide which heads to go with. I want the flow of the 3.0, but if I Extrude hone my 2.5 when their off, and throw on 3.0 valve with a good valve job, in conjunction w/ Pro-flow and 24# injectors (maybe larger if CR requires it) I should get a comparable setup, right? If I get enough pwr NA I won't go forced.

I wouldn't boost anything higher than 9:1 ... 10:1 and 11:1 are both useless for dependable boost. Sure, you might get it working knock free, but that won't last for long. Besides, even at 10:1, I highly doubt that you could run more than 6 psi without knock/detonation. Is all that trouble work 6 psi? I don't think so since you will only be satisfied with that power level for about 2 weeks and want to up the boost. I say do things right:

2001 3.0 longblock
forged rods
SHO bearings
low compression pistons

As for the 3.0's upper intake not fitting under the hood ... modify the hood while you are at it

I agree that low compression is better, 8.5:1 is preferable... BUT I think your statements above are pretty inaccurate. I have been running 8-10psi for over 10,000 miles with 10:1 compression & no intercooler without the trouble of knocking and predetonation. Infact the engine internals have outlasted the actual supercharger components!
-Mark

The last statement in Marks post really makes me want to go out and buy a Vortec supercharger......LOL. Did they improve the x-shaft?

The new shaft appears to be more a little beefier, but it doesn't appear to be hardened, nor does the prop shaft on the SC. IMO, I feel that what ever changes were made they are mearly a band-aid and the same failure will happen again.
If it does happen again then I have a back up plan and the SC & driveshaft are going in the trash.
-Mark

Myself and Buckshot77 are planning on a steel pin through the jackshaft/SC drive. Any thoughts Mark? Discussing threaded and cold welded pins so enertia doesn't pull it out...

A pin through the shaft... as in running the length or as in vertically in the center of the shafts end points?

-Mark

ummm... No.

2.5L valves are shrouded; 3L are not. big difference. Not enough meat to unshroud 2.5

Valve sizes! big difference. And if you bring up putting larger valves in the 2.5 the shrouding will be worse and the cost rises tremendously.

Another bonus IS dumping the stock waterpump pulley!

Vertically through the ends where it joins onto the S/C. Basically nothing more than an extra shear pin to keep the torque of the shaft turning the impeller from eating up those tiny little splines.

Rick